CN101188594A - OFDM transmission method - Google Patents
OFDM transmission method Download PDFInfo
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- CN101188594A CN101188594A CNA2007101997205A CN200710199720A CN101188594A CN 101188594 A CN101188594 A CN 101188594A CN A2007101997205 A CNA2007101997205 A CN A2007101997205A CN 200710199720 A CN200710199720 A CN 200710199720A CN 101188594 A CN101188594 A CN 101188594A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2602—Signal structure
- H04L27/2605—Symbol extensions, e.g. Zero Tail, Unique Word [UW]
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2626—Arrangements specific to the transmitter only
- H04L27/2627—Modulators
- H04L27/2637—Modulators with direct modulation of individual subcarriers
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2649—Demodulators
- H04L27/2653—Demodulators with direct demodulation of individual subcarriers
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2655—Synchronisation arrangements
- H04L27/2666—Acquisition of further OFDM parameters, e.g. bandwidth, subcarrier spacing, or guard interval length
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L5/00—Arrangements affording multiple use of the transmission path
- H04L5/0001—Arrangements for dividing the transmission path
- H04L5/0014—Three-dimensional division
- H04L5/0016—Time-frequency-code
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
- H04W52/04—TPC
- H04W52/18—TPC being performed according to specific parameters
- H04W52/26—TPC being performed according to specific parameters using transmission rate or quality of service QoS [Quality of Service]
- H04W52/267—TPC being performed according to specific parameters using transmission rate or quality of service QoS [Quality of Service] taking into account the information rate
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
- H04W52/04—TPC
- H04W52/18—TPC being performed according to specific parameters
- H04W52/28—TPC being performed according to specific parameters using user profile, e.g. mobile speed, priority or network state, e.g. standby, idle or non transmission
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2655—Synchronisation arrangements
Abstract
The invention relates to an orthogonal frequency division multiplexing transmission method. An expanding modulator (1) expands the frequency spectrum of a signal sequence. A sub-carrier modulator (2) utilizes the output of the expanding modulator (1) to modulate the frequencies of a plurality of sub-carriers with mutually different frequencies. An adder (3) combines the modulated sub-carriers. A guard gap control unit (23) determines the protection gap length according to the maximum transmission delay inequality of the communication link between a transmitting device and a receiving device. A guard gap plug-in unit (21) is controlled by the guard gap control unit (23) in order to plug the guard gap into the signal sequence of each symbol period. A gain adjusting device (22) leads the transmission signal to be multiplied by the gain factor corresponding to the plugged guard gap.
Description
The application is to be November 28 calendar year 2001 the applying date, and application number is 01823836.X, and denomination of invention is divided an application for " OFDM transfer method ".
Technical field
The present invention relates to a kind of OFDM and code division multiplexing (OFDM-CDM) transmission system, transmitter (modulator) and receiving equipment (demodulator) with this system, in particular, relate to a kind of be used between the base station of cell phone system or mobile phone communication system and mobile radio station, realizing communicating devices and method.
Background technology
Routinely, OFDM (hereinafter referred to as OFDM (OFDM)) transmission system is used for land Digital Television etc.In the OFDM transmission system, a plurality of subcarriers that the data utilization has different frequency transmit.In fact, in this system, a plurality of mutually orthogonal subcarrier-modulated transmission data, these subcarriers are by frequency division multiplexing and transmission.In the OFDM transmission system, even carry out high speed data transfer, also can reduce transmission rate, that is to say that transmission rate can be owing to every subcarrier reduces.Therefore, the influence of multipath interference can reduce.The OFDM transmission system for example " the CDMA multiple carrier outline,, (A.F.Molisch Prentice Hall PTR; calendar year 2001 describes in ISBN:0-13-022333-6) for (people such as Hare; ieee communication magazine, in December, 1997,126-133 page or leaf) or " Wideband Wireless Digital Communication ".
Fig. 1 represents to be used for the structure of the existing transmitter of OFDM transmission system.In this system, suppose transmitter multiplexed signals sequence Si and burst Sj and export them.The symbol period of also supposing burst Si and burst Sj is " T ".In addition, burst Si for example can be the signal that will be transmitted into different mobile radio stations with burst Sj.Otherwise the data that will be transmitted into a plurality of mobile radio stations can be to carry out time division multiplexing with burst Si.
Every section symbolic information of burst Si walks abreast and is input to m the input that expending modulator 1 is provided.That is to say that identical symbolic information is at parallel each input that is input to expending modulator 1 of each symbol period T.Then, expending modulator 1 utilizes allocates the symbolic information of modulating input to the extended code Ci of burst Si in advance, and exports the spread signal of the m bit that obtains.The structure of extended code Ci is that " Ci (1) " arrives " Ci (m) ", and is an element of orthogonal code sequence.
Δω＝2πΔf＝2π/T
As shown in Figure 2, protection is inserted the protection of for each symbol predetermined fixed being determined unit 4 at interval and is inserted into the composite signal of exporting from adder 3 at interval.Insert protection at interval in order to eliminate the multi-path influence of wireless transmission link.Fig. 2 represents to be inserted into the protection state at interval of each subcarrier.In fact, these subcarriers are combined.
Fig. 3 represents to be used for the structure of the existing receiving equipment of OFDM transmission system.Suppose receiving equipment received signal sequence Si from the wireless signal of Launch Equipment Shop emission shown in Figure 1.In Fig. 3, the required Frequency Synchronization ability of received signal, synchronizing capacity etc. have regularly been omitted.
The signal that antenna 11 is received converts baseband signal Srx to by receiver 12, converts m burst that has received to by subcarrier demodulator 13 then.Then, protection interval delete cells 14 is deleted protection at interval from the burst that each has received.Each burst that has received for inverse expansion, the burst that spread demodulation device 15 has received each multiply by the extended code identical extended code Ci used with transmitter.Then, by each signal of exporting from spread demodulation device 15 with adder 16 additions, regenerated signal sequence Si.
Between transmitter with said structure and receiving equipment, burst Si utilizes a plurality of subcarrier f1～fm emission, as shown in Figure 2.Burst Si be value for "+1,, or the symbolic information of " 1 ".That is to say that burst Si becomes "+1 " or " 1 " in symbol period T.In addition, the signal that utilizes each subcarrier f1～fm emission by extended code Ci (be respectively Ci (1), Ci (2) ..., Ci (m)) expand modulation.In Fig. 2, the output that the bit that indicates " * " represents to expand modulation is opposite (conjugation) output, because burst Si is " 1 ".
As mentioned above, protection is inserted into transmitting of each symbol at interval.In example shown in Figure 2, insert protection interval T g at symbol period T.Therefore, at receiving equipment, carry out the interval (interval T s) that inverse expansion/demodulating process obtains remove protection interval T g from each subcarrier after.Therefore, can eliminate multipath at receiving equipment and disturb (postponing the interference that ripple produced).
Disturb to eliminate multipath because insert protection interval T g, so the length longer than the maximum transmitting time delay difference of transmitting chain must be set." maximum transmitting time delay is poor " is meant poor when minimum propagation time that signal obtains and maximum propagation time when transmitter is transferred to receiving equipment by a plurality of paths.For example, in Fig. 4, suppose at first to arrive path 1 by the signal of path 1 transmission, the signal by path 3 transmission arrives receiving equipment at last, and the maximum transmitting time delay difference is represented with the difference in the propagation time in propagation time in path 3 and path 1 so.
But in cellular communication system, wireless signal is a plurality of base stations from a base station to service area usually.The maximum transmitting time delay difference of the signal from the base station to the mobile radio station becomes big along with the increase of distance between them.Suppose that multipath disturbs and to eliminate in all mobile radio stations from service area that farthest the multipath of mobile radio station disturbs also and must eliminate from the base station so.Therefore, if multipath disturbs and will eliminate in all mobile radio stations from service area, protect interval T g must be arranged to than base station transmit signals so to farthest the maximum transmitting time delay difference of mobile radio station is bigger from the base station.For example, in example shown in Figure 5, protection interval T g must be arranged to bigger to the maximum transmitting time delay difference that mobile radio station MS3 obtains than base station transmit signals.
But if determine the poor of protection interval as mentioned above, when signal was transmitted into the mobile radio station nearer from the base station (the mobile radio station MS1 among Fig. 5), protection at interval needn't be so long so.Simultaneously, when burst when receiving equipment is regenerated, do not use the protection blank signal power.Therefore, if determine protection as mentioned above at interval, then when being transmitted into mobile radio station, wasted signal power.As a result, total emission capacity of whole communication system reduces.
Summary of the invention
The objective of the invention is to utilize OFDM and code division multiplexing (OFDM-CDM) transmission system to improve the efficiency of transmission of signal in the communication system.
Communication system according to the present invention utilizes OFDM to transmit signal to receiving equipment from transmitter.This transmitter comprises modulating unit, is used to utilize burst to modulate a plurality of subcarriers; Insert the unit, be used for protection is inserted at interval the output of modulating unit; And transmitter unit, be used to launch the modulation signal that has inserted the protection interval.Receiving equipment comprises demodulating unit, is used for by carrying out the delete procedure of deleting the protection interval and each subcarrier being carried out demodulating process from the modulation signal of transmitter emission come the regenerated signal sequence.Protection length is at interval determined according to the communication environment between transmitter and the receiving equipment.
In this communication system, determine protection length at interval according to the communication environment between transmitter and the receiving equipment.That is to say that according to the communication environment between transmitter and the receiving equipment, protection length at interval can be short as much as possible, strengthens communication efficiency thus.
In above-mentioned structure, transmitter can also comprise power control unit, the through-put power when being used for coming the control transmission modulation signal according to protection length at interval.According to this structure, the through-put power of transmission signal sequence can be as much as possible little.Therefore, the interference between signal can reduce.
And in above-mentioned structure, receiving equipment can also comprise monitor unit, is used for determining protection length at interval thus, with the communication quality that obtains to be scheduled in signal monitor communication quality when transmitter is sent to receiving equipment.According to this structure, can be provided with and satisfy the short protection interval of most probable of wanting communication quality.
Another aspect according to communication system of the present invention is to be used for transmitting the communication system of signal to a plurality of receiving equipments from transmitter, and these receiving equipments comprise first receiving equipment that utilizes OFDM.This transmitter comprises modulating unit, be used for utilizing a kind of like this burst to modulate a plurality of subcarriers, this burst is that multiplexing first burst that is sent to first receiving equipment obtains with the secondary signal sequence that is sent to another receiving equipment that is different from first receiving equipment; Insert the unit, be used for first protection is inserted into the modulated output of first burst at interval and protects the modulated output that is inserted into the secondary signal sequence at interval with second; And transmitter unit, be used to launch and inserted the first protection interval and second protection modulation signal at interval respectively.First receiving equipment comprises demodulating unit, is used for by carrying out deletion first protection delete procedure and demodulating process first burst of regenerating at interval.First protection length at interval determines that according to the communication environment between the transmitter and first receiving equipment second protection length is at interval determined according to the communication environment between transmitter and another receiving equipment.According to this structure, when a plurality of bursts transmit, can suitable protection be set at interval in time division multiplex system for each burst.
Description of drawings
Fig. 1 represents to be used for the structure of the existing transmitter of OFDM transmission system;
Fig. 2 represents the example of the transmission signals in the existing OFDM transmission system;
Fig. 3 represents to be used for the structure of the existing receiving equipment of OFDM transmission system;
Fig. 4 is the key-drawing of multi-path environment;
Fig. 5 represents to hold the base station of a plurality of mobile radio stations;
Fig. 6 represents the structure according to the transmitter of the embodiment of the invention;
Fig. 7 represents the structure according to the receiving equipment of the embodiment of the invention;
Fig. 8 and 9 expressions are according to the example of the transmission signals in the OFDM transmission system of the embodiment of the invention;
Figure 10 is a protection key-drawing at interval;
Figure 11 is the key-drawing of the performed inverse Fourier transform of subcarrier modulator;
Figure 12 is the key-drawing that inserts the protection interval procedure;
Figure 13 represents to realize inserting the embodiment of the structure of protecting interval procedure;
Figure 14 represents to realize from receiving the embodiment of the structure of deletion protection interval procedure the ripple;
Figure 15 represents the structure according to the transmitter of first embodiment of the invention;
Figure 16 represents the structure according to the receiving equipment of first embodiment of the invention;
Figure 17 represents the schematic diagram according to the transmission signals in the communication system of first embodiment of the invention;
Figure 18 represents the structure according to the transmitter of second embodiment of the invention;
Figure 19 represents the structure according to the receiving equipment of second embodiment of the invention;
Figure 20 represents the schematic diagram according to the transmission signals in the communication system of second embodiment of the invention;
Figure 21 represents the structure according to the transmitter of third embodiment of the invention;
Figure 22 represents the structure according to the receiving equipment of third embodiment of the invention;
Figure 23 represents the structure of the example of delay inequality detecting unit shown in Figure 22;
Figure 24 is the key-drawing of delay inequality detecting unit operation;
Figure 25 represents to detect the example of maximum transmitting time delay difference;
Figure 26 represents the structure according to the transmitter of four embodiment of the invention;
Figure 27 represents the structure according to the receiving equipment of four embodiment of the invention;
Figure 28 represents the structure of the example of distance estimations shown in Figure 27 unit;
Figure 29 represents the structure according to the transmitter of fifth embodiment of the invention;
Figure 30 represents the structure according to the receiving equipment of fifth embodiment of the invention;
Figure 31 represents the structure of the example of timing generation unit shown in Figure 30;
Figure 32 represents the structure according to the transmitter of sixth embodiment of the invention;
Figure 33 represents the structure according to the receiving equipment of sixth embodiment of the invention;
Figure 34 represents the structure of the example of timing generation unit shown in Figure 33;
Figure 35 represents the structure according to the transmitter of seventh embodiment of the invention;
Figure 36 represents the structure according to the receiving equipment of seventh embodiment of the invention;
Figure 37 represents the operational flowchart of delay inequality detecting unit as shown in figure 36;
Figure 38 represents the structure according to the transmitter of eighth embodiment of the invention;
Figure 39 represents the structure according to the receiving equipment of eighth embodiment of the invention;
Figure 40 represents the operational flowchart of distance estimations shown in Figure 39 unit.
Embodiment
Embodiments of the invention are described with reference to the accompanying drawings.In the explanation hereinafter, suppose that OFDM and code division multiplexing (OFDM-CDM) transmission system is used for cellular communication system.In fact, for example, OFDM-CDM is used for transmission signals between base station and mobile radio station.
Fig. 6 represents the structure according to the transmitter of the embodiment of the invention.This transmitter is for example corresponding to the equipment of base station among Fig. 5.Suppose this transmitter multiplexing and output signal sequence Si and burst Sj.Burst Si for example can be the signal that will be sent to different mobile radio stations with burst Sj.Perhaps, be sent to a plurality of mobile radio stations data can with burst Si or burst Sj time division multiplexing.
Frequency modulator) 2, adder (SUM) 3, protection insert unit (GINS) 21 and fader (G) 22 at interval this transmitter comprises expending modulator (SMOD) 1, subcarrier modulator (FMOD:.Expending modulator 1, subcarrier modulator 2 and adder 3 can realize by the related circuit of explaining referring to Fig. 1.That is to say that expending modulator 1 has m input, identical symbolic information is at parallel each input that is input to expending modulator 1 of each symbol period T.Then, expending modulator 1 utilizes the extended code Ci that allocates in advance to each burst Si to modulate incoming symbol information, and exports the spread signal of the m bit that obtains.The structure of extended code Ci is that " Ci (1) " arrives " Ci (m) ", and is an element of orthogonal code sequence.
Δω＝2πΔf＝2π/T
The composite signal of above-mentioned each burst that obtains is added together by adder (ADD) 5, as the situation of existing transmitter shown in Figure 1.Then, the output of adder 5 converts predetermined high-frequency signal to by transmitter (TX) 6, then by antenna 7 emissions.
Therefore, in transmitter according to the present invention, insert the protection interval of determining according to the communications status between transmitter and the receiving equipment.For each burst that will transmit (Si, Sj), the amplitude of transmission signals or power are adjusted corresponding to insert protection each length at interval.
Fig. 7 represents the structure according to the receiving equipment of the embodiment of the invention.In this example, receiving equipment hypothesis received signal sequence Si from the wireless signal of transmitter emission shown in Figure 6.This receiving equipment is for example corresponding to the mobile radio station of Fig. 5.In Fig. 7, the required Frequency Synchronization ability of received signal, synchronizing capacity etc. have regularly been omitted.
The signal that antenna 11 is received converts baseband signal Srx to by receiver (RX) 12, then by subcarrier demodulator (FDEM: frequency demodulator) 13 convert the burst that has received to.Subcarrier demodulator 13 has m input, the parallel input that is input to of identical baseband signal Srx.Subcarrier demodulator 13 multiply by the periodic wave that angular frequency is ω 1～ω m with baseband signal Srx, thus each subcarrier signals of demodulation.The process of subcarrier demodulator 13 for example realizes by Fourier transform.
Protection delete cells 31 is at interval deleted protection at interval from the burst that each has received under the instruction of protection interval control unit (GCNTi) 32.Protection interval control unit 32 is discerned the protection length of in the transmitters burst Si being inserted at interval, and this value is notified to protection delete cells 31 at interval.Therefore, protection interval delete cells 31 can correctly be eliminated the protection interval that Launch Equipment Shop inserts.
Fig. 8 and 9 expressions are according to the example of the transmission signals in the OFDM transmission system of the embodiment of the invention.Fig. 8 is that transmission signals will be sent to the schematic diagram that is positioned at the less mobile radio station of maximum transmitting time delay difference (receiving equipment).Fig. 9 is that transmission signals will be sent to the schematic diagram that is positioned at the bigger mobile radio station of maximum transmitting time delay difference (receiving equipment).The symbol period of transmission signals shown in Figure 8 is " T1 ", and the symbol period of transmission signals shown in Figure 9 is " T2 ".These two symbol periods can be identical, also can be different.
When signal will be sent to when being positioned at the less mobile radio station of maximum transmitting time delay difference, protection interval T g1 is inserted into the symbol period T1 of each subcarrier, as shown in Figure 8.Therefore, signal utilizes regional Ts1 to transmit.On the other hand, when signal will be sent to when being positioned at the bigger mobile radio station of maximum transmitting time delay difference, protection interval T g2 is inserted into the symbol period T2 of each subcarrier, as shown in Figure 9.Therefore, signal utilizes regional Ts2 to transmit.Here, protection interval T g1 shorter than protection interval T g2 with being provided with.That is to say that when the maximum transmitting time delay difference that is detected when signal was big, protection length at interval will be grown accordingly when transmitter is sent to receiving equipment.
When signal will be sent to when being positioned at the less mobile radio station of maximum transmitting time delay difference, the through-put power of signal is controlled to be " P1 ", as shown in Figure 8.On the other hand, when signal will be sent to when being positioned at the bigger mobile radio station of maximum transmitting time delay difference, the through-put power of signal is controlled to be " P2 ", as shown in Figure 9.Here, power P 2 is greater than power P 1.That is to say that when the maximum transmitting time delay difference that is detected when signal was big, it is big that the through-put power of signal is wanted accordingly when transmitter is sent to receiving equipment.
Then, before explaining protection insertion/deletion at interval, explain protection interval itself briefly.
Figure 10 is a protection key-drawing at interval, the schematic diagram of expression receiving equipment received signal waveform.Solid line " a " expression at first arrives the signal waveform " basic wave " of receiving equipment, and dotted line " b " expression arrived the inhibit signal waveform " delay ripple " of receiving equipment afterwards.In Figure 10, only having drawn one postpones ripple, but in fact two or more delay ripples are arranged.
In Figure 10, before time T 1, because basic wave and delay ripple are continuous sine waves, the corresponding symbolic information so receiving equipment can be regenerated from composite wave.But when symbolic information becomes " 1 " from "+1 ", or when " 1 " became "+1 ", the signal phase of transmission symbol information moved.In example shown in Figure 10, the phase place of basic wave moves in time T 1, and the phase place that postpones ripple moves in time T 2.That is to say that in this case, in the cycle between time T 1 and the time T 2, basic wave is in the later transmission information of phase shift, and delay ripple transmission information before phase shift.Therefore, during this period of time, a signal wave can be the disturbing wave of another signal wave, and symbolic information can not correctly regeneration from the ripple that has received.
The influence of above-mentioned interference can be avoided in example shown in Figure 10, promptly when receiving the ripple regenerated signal, and the ripple of reception between service time T1 and the time T 2 not.In the OFDM transmission system, comprise that the predetermined period in this cycle is defined as the protection interval that receiving equipment is not used in regenerated signal.Therefore, protection length at interval must be arranged to greater than the delay inequality (maximum transmitting time delay is poor) between the delay ripple of the signal wave of first arrival and last arrival.
But, as mentioned above, the maximum transmitting time delay difference along with between transmitter and the receiving equipment the distance etc. and change.Therefore, in the communication system according to the embodiment of the invention, protection length is at interval determined according to the maximum transmitting time delay difference.
Next explain that transmitter inserts protection method at interval.In this example, the process of supposing subcarrier modulator 2 shown in Figure 6 realizes by inverse Fourier transform.
Figure 11 represents by the performed inverse Fourier transform of subcarrier modulator 2.In this process, " T " represents symbol period, the protection that " Tg " expression is inserted into each symbol period at interval, " Ts (=T-Tg) " represents the signal time of each symbol period.
As mentioned above, the m segment information from expending modulator 1 output is input to subcarrier modulator 2.Every segment information is assigned to the subcarrier with corresponding frequencies.That is to say that subcarrier modulator 2 is received in m the signal of arranging on the frequency axis.M on a frequency axis signal converts the burst of m sample value on the time shaft to by the inverse Fourier transform of carrying out at each symbol period T, as shown in figure 11.At this moment, the sample value of the m on the time shaft is arranged among the signal time Ts.
Figure 12 is the key-drawing that the protection interval procedure is inserted in expression.After receiving m the sample value that signal time Ts arranges, protection is inserted unit 21 at interval and is protected the sample value of the determined respective number of interval T g from the last extraction of signal time Ts, and is right after before signal time Ts and duplicates them.In example shown in Figure 12, interval T g is corresponding to three sample times in protection, extraction " m-2 ", " m-1 " and " m " from m sample value " 1 "～" m ", and be right after before signal time Ts and duplicate them.In reproduction process, be created in the symbol time (burst of=Tg+Ts) time shaft.
Figure 13 represents to realize inserting the embodiment of the structure of protecting interval procedure.As mentioned above, subcarrier modulator 2 realizes by the inverse Fourier transform device, and m conversion of signals of frequency axis become m the sample value (t1～tm) of the time shaft of each symbol period.Then, protection insert at interval unit 21 read successively with output protection interval T g in " tm-2 ", " tm-1 " and " tm ", at signal time Ts subsequently, read successively and export " t1 "～" tm ".Therefore, produce the burst that has inserted the protection interval.
According to above-mentioned structure, protection length is at interval controlled by changing " the sample value number of output before the signal time Ts ".In this case, determine the readout interval of sample value, so that protection interval T g, signal time Ts and inverse Fourier transform cycle (that is symbol period T) can be satisfied predetermined relation (T=Tg+Ts).
The following describes an example.In this example, conventional letter cycle=T, protection interval T g=0.2T, signal time Ts=0.8T, the number of sub carrier wave that be re-used is " m=1000 ".In this case, 1000 sample value (t1～t1000) be input to protection to insert unit 21 at interval at each symbol period.Then, 250 (=1000 * 0.2 ÷ 0.8) sample value (t750～t1000) at first read and export.Then, 1000 sample value (t1～t1000) be read out and export.At this moment, the readout interval of sample value is " T/1250 ".If protection interval T g=0.1T, signal time Ts=0.9T, number of sub carrier wave " m=1000 "; then protection is inserted at interval unit 21 and is at first read and export the individual sample value of 111 (=1000 * 0.1 ÷ 0.9) (t890～t1000), and read and export 1000 sample values (t1～t1000) subsequently.At this moment, the readout interval of sample value is " T/1111 ".
In an embodiment of the present invention, just insert protection at interval later at a plurality of subcarriers of combination.But, can insert protection at interval for each subcarrier in principle.
Figure 14 is illustrated in receiving equipment and realizes from receiving the embodiment of the structure of deletion protection interval procedure the ripple.In this example, receive the burst that shown in Figure 11 to 13, produces (tm-2, tm-1, tm, t1, t2, t3 ..., tm).In receiving equipment shown in Figure 7, the demodulation subcarrier is deleted protection later at interval.But in structure shown in Figure 14, these processes are done as a whole the execution.
Protection delete cells 31 at interval comprises switch 41, shift register 42.Receive burst (tm-2, tm-1, tm, t1, t2, t3 ..., tm) after; protection at interval delete cells 31 suitably opens or closes sample value that switch 41 is arranged in the predetermined number in the protection at interval with deletion (in this example; tm-2, tm-1, tm), (t1～tm) is sent to shift register 42 to the sample value of m subsequently.Protection is the protection length (or the sample value number in the protection at interval) at interval of delete cells 31 identification Launch Equipment Shops insertions at interval, comes the open/close state of control switch 41 according to it.On the other hand, when m sample value is accumulated in the shift register 42, serves as the Fourier transformer of subcarrier demodulator 13 sample value is carried out Fourier transform, obtain being used for each subcarrier signals f1～fm thus.This process repeats at each symbol period T.
As mentioned above, in cellular communication system according to the embodiment of the invention, when signal when transmitter (base station) is sent to receiving equipment (mobile radio station), protection length and through-put power at interval determined according to the maximum transmitting time delay difference between them.Here, the distance between transmitter and receiving equipment hour, the maximum transmitting time delay difference is less, protection is shorter at interval.When protection shortened at interval, the used signal time of receiving equipment regenerated signal was just elongated.Therefore, through-put power can be littler.Therefore the interference power of whole system is minimized, and has successfully increased transmission capacity.
That describe below is the embodiment of above-mentioned transmitter and receiving equipment.
First embodiment:
Figure 15 and 16 expressions are according to the structure of transmitter and the receiving equipment of first embodiment.The basic structure of these equipment and transmitter shown in Figure 6 and receiving equipment shown in Figure 7 are identical.But the transmitter according to first embodiment can come a plurality of time-multiplexed bursts of common modulation with an OFDM-CDM unit (unit 21 is inserted in expending modulator 1, subcarrier modulator 2, adder 3 and protection at interval).
That is to say that burst Si1 and burst Si2 are multiplexing by time-division multiplexing unit shown in Figure 17 (TDMi) 51.In this example, these bursts transmit by the communication link with different maximum transmitting time delay differences.These bursts are modulated by expending modulator 1 and subcarrier modulator 2, offer protection then and insert unit 21 at interval.
Protection is inserted unit 21 at interval and will be inserted in the input signal sequence at interval than the wide protection of corresponding maximum transmitting time delay difference.The protection of each burst is provided with by protection interval control unit 23 at interval.Fader 22 multiply by transmission signals the gain coefficient α that determines at interval according to insert protection.In fact, in example shown in Figure 17, when input signal sequence Si1, protection interval T g1 is inserted into each symbol period, and ride gain factor alpha i (t) is so that the through-put power of signal is " P1 ".On the other hand, when input signal sequence Si2, protection zone Tg2 is inserted into each symbol period, and ride gain factor alpha i (t) is so that the through-put power of signal is " P2 ".
The signal of above-mentioned modulation and the signal combination of another sequence, and launch by antenna 7.
The basic operation of receiving equipment has been described referring to Fig. 7 above.But this receiving equipment can only refresh address be the signal of this equipment itself.For example, when burst Si1 regenerates from the signal that time multiplexing signal sequence Si1 and burst Si2 obtain, protection interval control unit 32 to protection at interval delete cells 31 send instruction with the protection interval T g1 of deletion received signal sequence Si1 in the cycle.Then, under this instruction, the protection in each symbol period of protection interval delete cells 31 erasure signal sequence Si1 at interval.At this moment, in the cycle of received signal sequence Si2, do not delete protection at interval.
The protection output of delete cells 31 is at interval carried out the inverse expansion demodulation by spread demodulation device 15.At this moment, spread demodulation device 15 is carried out the inverse expansion demodulation in the signal time Ts1 that has deleted protection interval T g1.Demultiplexing unit (DML) 52 is dateout in corresponding to the time slot of the burst Si1 of demodulated signal.
Therefore, in the communication system according to first embodiment of the invention, a plurality of time-multiplexed bursts can come common modulation by an OFDM-CDM unit (unit 21 is inserted in expending modulator 1, subcarrier modulator 2, adder 3 and protection at interval).
Second embodiment:
Communication system according to second embodiment of the invention is the modification of the communication system of first embodiment.That is to say that in the system according to first embodiment, time-multiplexed burst Si1 and burst Si2 utilize OFDM-CDM to transmit.Suppose that burst Si1 and burst Si2 are sent to the corresponding mobile station.On the other hand, in the system according to second embodiment, time-multiplexed broadcast message Bi and burst Si1 utilize OFDM-CDM to transmit.Burst Si1 is sent to one or more receiving equipments, but broadcast message Bi is sent to all receiving equipments (mobile radio station) of service area.Therefore, protection interval and definite through-put power must be set like this, be positioned at service area receiving equipment (that is the receiving equipment that, has maximum maximum transmitting time delay difference) farthest so that broadcast message Bi can correctly be sent to.
Figure 18 and 19 expressions are according to the structure of the transmitter and the receiving equipment of second embodiment of the invention.The basic structure of these equipment and transmitter shown in Figure 15 and receiving equipment shown in Figure 16 are identical.
In second example; the instruction of unit 21 according to protection interval control unit 23 inserted in protection at interval; in each symbol period of input broadcast message Bi, insert protection interval T g1, and in each symbol period of input signal sequence Si1, insert protection interval T g2, as shown in figure 20.It is poor that the protection interval T g1 that is inserted into broadcast message Bi is arranged to the maximum transmitting time delay of the maximum that produces greater than service area.For example, if be maximum from the base station to the maximum transmitting time delay difference in mobile radio station MS3 path, transmit broadcast message to mobile radio station MS1 during to MS3 when the base station among Fig. 5, it is poor then to protect the length of interval T g1 to be arranged to greater than this maximum transmitting time delay.On the other hand, the protection interval T g2 that is inserted into burst Si1 be arranged to greater than maximum transmitting time delay to the corresponding reception device path poor.For example, when burst Si1 when the base station of Fig. 5 is sent to mobile radio station MS1, the length of protection interval T g2 is arranged to greater than poor to the maximum transmitting time delay in MS1 path from the base station.
In receiving equipment, the protection interval T g2 during protection interval control unit 32 is illustrated in the protection interval T g1 during the receiving broadcasting information Bi and is illustrated in received signal sequence Si1.Protection delete cells 31 is at interval deleted protection at interval from received signal under the instruction of protection interval control unit 32.In addition, having deleted protection signal at interval by spread demodulation device 15 inverse expansion, is broadcast message Bi and burst Si1 by demultiplexing unit 52 demultiplexings then.
The length that is inserted into the protection interval T g1 of broadcast message Bi for example comes to determine like this.
(1) determines according to the size of communication zone.That is to say that the size of the communication zone that covers according to Launch Equipment Shop estimates that broadcast message Bi postpones the time of delay of the receiving equipment that arrives at last, and according to the length of determining protection interval T g1 this time of delay.
The through-put power of the transmitter during (2) according to transmission broadcast message Bi is determined.That is to say that estimate that according to the through-put power of broadcast message Bi broadcast message Bi is sent to the maximum in the propagation delay time of a plurality of receiving equipments, the length of protection interval T g1 is according to determining time of delay.
(3) determine according to the communication environment of a plurality of receiving equipments in the communication zone.That is to say, obtain each pairing communication environment of a plurality of receiving equipments in the communication zone that Launch Equipment Shop covers, determine the length of protection interval T g1 according to this communication environment.In fact, the length of protection interval T g1 is determined according to having the receiving equipment of poor communication environment.
(4) determine according to the maximum delay time in the communication zone.That is to say, measure in communication zone for each receiving equipment and transmit the time of delay of broadcast message Bi that the length of protection interval T g1 is determined according to the maximum delay time of measurement result to a plurality of receiving equipments from transmitter.
The 3rd embodiment
In the communication system according to third embodiment of the invention, it is poor to the maximum transmitting time delay of receiving equipment to detect from transmitter transmission signal, and protection interval and through-put power are determined according to testing result.In order to realize this function, transmitter and the receiving equipment of the 3rd embodiment have necessary ability.
Figure 21 represents the structure according to the transmitter of third embodiment of the invention.Transmitter receives maximum transmitting time delay difference information (τ), and the maximum transmitting time delay that is illustrated in the corresponding reception device detection is poor, and has the function of determining protection interval and through-put power according to this information.That is to say that protection interval control unit (GINSCNT) 61 is according to the definite protection gap length that will insert of the maximum transmitting time delay difference that detects at corresponding reception device.In fact.Protection interval control unit 61i is according to the maximum transmitting time delay difference information (τ i) that the receiving equipment of received signal sequence Si1 and/or burst Si2 transmits, and the protection of determining to be inserted into the signal that is used to transmit burst Si1 and/or burst Si2 at interval.Power control unit (PCNT) 62 is determined gain coefficient α according to the maximum transmitting time delay difference that detects at corresponding reception device.In fact, power control unit 62i determines gain coefficient α according to the maximum transmitting time delay difference information (τ i) that the receiving equipment from received signal sequence Si1 and/or burst Si2 transmits, and is used to transmit the signal times of burst Si1 and/or burst Si2 with gain coefficient α.
Protection is inserted the protection that will protect interval control unit 61 to determine at each symbol period in unit 21 at interval and is inserted into transmission signals at interval.Fader 22 is realized corresponding to the through-put power of protecting gap length by transmission signals being multiply by power control unit 62 definite gain coefficient α.
Figure 22 represents the structure according to the receiving equipment of third embodiment of the invention.This receiving equipment has the function of detection from the maximum transmitting time delay difference of the signal of transmitter transmission.That is to say that delay inequality detecting unit (DMES) 63 detects maximum transmitting time delay from the baseband signal Srx that receives poor, and notify the maximum transmitting time delay difference information of representing testing result to protection interval control unit 64 and corresponding transmitter.Protection interval control unit 64 is protected at interval according to determining from the notice of delay inequality detecting unit 63, and protection interval delete cells 31 is given in expression.Protection delete cells 31 is at interval protected at interval according to this expression deletion from wireless signal.
Figure 23 represents the structure of an example of delay inequality detecting unit 63 shown in Figure 22.Delay inequality detecting unit 63 comprises: be used for the delay circuit 71 with baseband signal Srx Ts time of delay; The correlation detecting circuit 72 that comprises multiplier 72a and integrator 72b; Be used for the correlation that comparison correlation detecting circuit 72 detected and the comparison circuit 73 of predetermined threshold; With the testing circuit 74 that is used for detecting the maximum transmitting time delay difference according to the comparative result of comparison circuit 73.Multiplier 72a multiply by time delayed signal with baseband signal Srx.The output of integrator 72b integration multiplier 72a.The operation of delay inequality detecting unit 63 is by explaining referring to Figure 24.
Baseband signal Srx and the signal (inhibit signal) of baseband signal Srx Ts time of delay is input to correlation detecting circuit 72.Protection interval T g at each symbol period duplicates shown in Figure 11 to 13 in the sample value of signal time Ts afterbody.Therefore, between baseband signal Srx and inhibit signal, correlation (auto-correlation) strengthens when the protection interval overlapping of the afterbody of baseband signal Srx and inhibit signal.But as mulitpath, these paths have propagation delay time different between transmitter and the receiving equipment, all can occur the peak value of correlation during at every turn by every link received signal.Therefore, when this correlation is compared with predetermined threshold by comparison circuit 73, can detect the timing that signal receives by every paths.Therefore, to detect maximum transmitting time delay poor the timing by measure receiving first signal and time difference of receiving the timing of last signal.For example, in communication environment shown in Figure 4, the maximum transmitting time delay difference detects as shown in figure 25.
Therefore, in the 3rd embodiment, the maximum transmitting time delay difference in path is measured between transmitter and the receiving equipment, and protection is at interval according to this measurement result insertion/deletion.Therefore, the protection interval width can dynamically change.And, because the gain coefficient of transmission signals determines according to the measurement result of maximum transmitting time delay difference, so through-put power can be reduced to minimum possible value always.
The 4th embodiment
In the communication system according to four embodiment of the invention, the transmission range between transmitter and the receiving equipment is estimated that this protection interval and through-put power are determined according to this estimated result.Therefore, transmitter and the receiving equipment according to four embodiment of the invention has the ability that can realize above-mentioned purpose.
Figure 26 represents the structure according to the transmitter of four embodiment of the invention.This transmitter has the function that receives transmission range information (L), and this information representation arrives the estimated value of the transmission range of corresponding reception device, and determines protection interval and through-put power according to this information.That is to say that protection interval control unit (GINSCNT) 81 is according to the definite protection that will insert of the transmission range between transmitter and receiving equipment length at interval.In fact; 81i is according to the transmission range information (Li) that receiving equipment transmitted from received signal sequence Si1 and/or burst Si2 for the protection interval control unit, determines to be inserted into the protection interval of the signal that is used for transmission signal sequence Si1 and/or burst Si2.Power control unit (PCNT) 82 determines gain coefficient α according to above-mentioned transmission range.In fact, power adjustment unit 82i determines and the gain coefficient α that is used for the signal multiplication of transmission signal sequence Si1 and/or burst Si2 according to the transmission range information (Li) that receiving equipment transmitted from received signal sequence Si1 and/or burst Si2.
Then, the transmission signals that the protection that will protect interval control unit 81 to determine in unit 21 is inserted into each symbol period is at interval inserted in protection at interval.And fader 22 is realized corresponding to the through-put power of protecting gap length by transmission signals being multiply by power control unit 82 definite gain coefficient α.
Figure 27 represents the structure according to the receiving equipment of four embodiment of the invention.This receiving equipment has the function of estimating transmission range between transmitter and the receiving equipment.That is to say that distance estimations unit (LMES) 83 is according to the transmission range between baseband signal Srx estimation transmitter that has received and the receiving equipment, the transmission range information L of expression estimated result is sent to protection interval control unit 84 and corresponding transmitter.Protection interval control unit 84 is protected at interval according to determining from the notice of distance estimations unit 83, and protection interval delete cells 31 is given in expression.Protection delete cells 31 is at interval deleted this protection at interval according to this expression from received signal.
Figure 28 represents an example of structure of distance estimations shown in Figure 27 unit 83.Distance estimations unit 83 comprises the conversion table 85 that delay inequality detecting unit 63 and the 3rd embodiment of top reference explain.
Distance between transmitter and the receiving equipment is poor corresponding to the maximum transmitting time delay of communication link between them.Transmission range is long more, and the maximum transmitting time delay difference is big more.Therefore, can estimate transmission range by detecting the maximum transmitting time delay difference, if in experiment, simulation etc., obtain the relation between them.Therefore, about the information stores that concerns between transmission range and the maximum transmitting time delay difference in the conversion table 85 of distance estimations unit 83.Transmission range between transmitter and the receiving equipment is by estimating the delay inequality detecting unit 63 maximum transmitting time delay difference that detects as keyword retrieval conversion table 85 then.
The 5th embodiment
In the communication system according to fifth embodiment of the invention, as the 4th embodiment, the transmission range between transmitter and the receiving equipment is estimated that this protection interval and through-put power are determined according to this estimated result.But, be different from the method for the 4th embodiment of data according to the method for estimation of the 5th embodiment.
Figure 29 represents the structure according to the transmitter of fifth embodiment of the invention.This transmitter has the function that receives timing information (T) from corresponding receiving equipment; and according to the transmission range between information estimation transmitter that has received and the receiving equipment with according to the definite function of protecting interval and through-put power of the estimated value of transmission range.
Protection interval control unit (GINSCNT) 91 or power control unit (PCNT) 92 are according to the transmission range of estimating from the timing signal T that corresponding reception device transmitted between transmitter and the receiving equipment.That is to say that in the 5th embodiment, signal is launched from transmitter, this signal is detected by corresponding receiving equipment, turns back to transmitter about the information of receiving equipment institute detection signal.The timing of receiving equipment detection signal utilizes temporal information T to be notified to transmitter.Therefore; if protection interval control unit 91 or power control unit 92 monitor from time that signal is sent to receiving equipment up to timing information T from the time that corresponding reception device returns, it can estimated transmission time and transmitter and receiving equipment between transmission range.The estimated value of transmission range utilizes transmission range information L to be notified to corresponding receiving equipment.
Protection interval control unit 91 is determined protection length at interval according to the estimated value of transmission range.Power control unit 92 is determined gain coefficient α according to the estimated value of transmission range.These processes are identical with the 4th embodiment.
Figure 30 represents the structure according to the receiving equipment of fifth embodiment of the invention.This receiving equipment has the reception function regularly that detects Launch Equipment Shop transmission signal.That is to say that regularly generation unit (TGEN) 93 detects according to the baseband signal Srx that has received and receives regularly, and generates timing signal T.The timing signal T that is generated then is sent to transmitter.In addition, protection interval control unit (GCNT) 94 is determined protection at interval according to the transmission range information L from transmitter, and protection delete cells 31 is at interval given in expression.Protection delete cells 31 is at interval protected at interval according to this expression deletion from received signal.
Figure 31 represents the structure of an example of timing generation unit 93 shown in Figure 30.Regularly generation unit 93 comprises that correlation detecting circuit 72 and maximum that delay circuit 71 and the 3rd embodiment of top reference describe determine circuit 95.
When being correlated with between wireless signal and the inhibit signal thereof was monitored as mentioned above, the correlation that receives the protection gap periods was higher.In fact, detect the maximum of correlation in each symbol period by determine circuit 95 with maximum, protection timing (perhaps being close to timing constantly after protecting at interval) at interval can be detected.Regularly production unit 93 generates expression and detects timing information T regularly, and it is sent to transmitter.
The 6th embodiment
According to the communication system estimation transmitter of the 6th embodiment and the transmission range between the receiving equipment, protection interval and through-put power are determined according to estimated result.But the method for estimation of the 6th embodiment is different from the method for the 4th or the 5th embodiment.
In communication system according to the 6th embodiment, when burst Si1 and burst Si2 are transmitted, each burst and Given information SW time division multiplexing.On the other hand, as the receiving equipment detection Given information SW that received signal comprised, it detects regularly to the transmitter notice.Then, transmitter regularly and from the timing information that receiving equipment transmits detects transmission time of signal between transmitter and the receiving equipment according to the transmission of Given information SW, and estimates transmission range according to this transmission time.
Figure 32 represents the structure according to the transmitter of the 6th embodiment.Transmitter have multiplexing transmission burst and Given information SW function, receive timing information (T) and estimate the function of transmission range between transmitter and the receiving equipment and determine that according to the estimated value of transmission range protection at interval and the function of through-put power from corresponding receiving equipment according to the information that is received.
When time-division Multiplexing Unit 51 transmits burst Si1 and Si2, its multiplexed signals sequence and Given information SW.Given information SW does not make stipulations, but corresponding receiving equipment must can be discerned this data format.
Protection interval control unit (GINSCNT) 101 or power control unit (PCNT) 102 are according to the distance of estimating from the timing signal T that corresponding reception device transmitted between transmitter and the corresponding reception device.The estimated value of transmission range utilizes transmission range information L to be notified to corresponding receiving equipment.The method of estimation transmission range is described subsequently.
Protection interval control unit 101 is determined protection length at interval according to the estimated value of transmission range.Power control unit 102 is determined gain coefficient α according to the estimated value of transmission range.These processes process with the 4th or the 5th embodiment basically are identical.
Figure 33 represents the structure according to the receiving equipment of the 6th embodiment.This receiving equipment has from receiving the function of demultiplexing Given information SW the ripple, to the function of transmitter notice about the information of Given information reception.That is to say, when timing generation unit 103 (TGEN) detects from the Given information SW of demultiplexing unit (DML) 52 output, if pass by preset time then generate a timing signal and be sent to transmitter after detecting regularly.Protection interval control unit (GCNT) 104 is determined protection at interval according to the transmitting range information L that transmits from transmitter, and protection delete cells 31 is at interval given in expression.Then, protection interval delete cells 31 is protected at interval according to this expression deletion from received signal.
Figure 34 represents the structure of an example of timing generation unit 103 shown in Figure 33.The burst of receiving equipment institute demodulation is input to regularly generation unit 103.Here, this burst comprises the Given information SW that Launch Equipment Shop inserts.Burst is input to shift register 105 subsequently, and it has the word length identical with Given information SW.When each new data were write shift register, whether the data that logical inverse circuit 106, add circuit 107 and comparison circuit 108 checks have been stored mated with Given information SW.Logical inverse circuit 106 has been provided the corresponding word format with Given information SW.Add circuit 107 will be stored in the value of each element of shift register 105 or the logical inverse value that is stored in each element of shift register 105 adds together.Then, comparison circuit 108 is the addition results and the predetermined threshold of add circuit 107 relatively, output timing signal T when addition results is big.
Therefore, in the communication system according to the 6th embodiment, Given information SW is sent to receiving equipment from transmitter, informs to receiving equipment from transmitter about the information that Given information SW receives.Therefore, suppose " T1 " expression when the launch time of signal when transmitter is sent to receiving equipment, " Td " expression detects the time of Given information SW to the transmission timing information from receiving equipment; " T2 " expression is when the delivery time of timing information when receiving equipment is sent to transmitter, " T0 " expression is from transmitting Given information SW to the time that receives timing information, equation below satisfying supposes that " T2 " is directly proportional with " T1 ", and " β " represents proportionality constant.
T1＝T0-Td-T2
＝T0-Td-β·T1
Therefore,
T1＝(T0-Td)/(1+β)
Wherein the transmission range between transmitter and the receiving equipment and signal were directly proportional from the transmission time (T1) that transmitter is sent to receiving equipment.From receiving equipment detect Given information SW to the time (Td) of transmitting timing information be known.Therefore, by measuring the time (T0) from emission Given information SW to the reception timing information, transmitter can be estimated the transmission range between transmitter and the receiving equipment.In this embodiment, protection interval control unit 101 or power control unit 102 are estimated transmission range.
The 7th embodiment
In communication system according to seventh embodiment of the invention, to measure transmission error rate and change protection simultaneously at interval, protection length (and through-put power) at interval is defined as reserving predetermined communication quality.Therefore, transmitter and the receiving equipment according to the 7th embodiment has the function that realizes above-mentioned purpose.
Figure 35 represents the structure according to the transmitter of seventh embodiment of the invention.This transmitter has the function and reception maximum transmitting time delay difference information (τ) of modulating and transmitting known format data (PLj) and the function of determining protection interval and through-put power according to reception information.
Known format data (PLj) are by expending modulator 1 expansion, then by subcarrier modulator 2 modulation.Known format data (PLj) are regulation not, but it is wanted and can be discerned by each receiving equipment.Expending modulator 1 utilizes extended code C (PLj) the expansion known format data (PLj) corresponding to known format data (PLj).
Protection is inserted unit (GINSj) 21 at interval relatively long protection is inserted into the burst that is used to transmit known format data (PLj) at interval.For example supposing that signal is sent to is positioned at service area mobile radio station (receiving equipment) farthest, determines that protection at interval.Fader (Gj) 22 multiply by suitable gain coefficient α j, can enough big through-put power transmit so that insert protection burst at interval.For example supposing that signal is sent to is positioned at service area mobile radio station (receiving equipment) farthest, determines gain coefficient α j.Known format data (PLj) are multiplexing with burst Si1 and Si2, then emission.
The 3rd embodiment of top reference that operate in of protection interval control unit (GINSCNT) 61 and power control unit (PCNT) 62 is described.That is to say that protection interval control unit 61 is according to the definite protection that will insert of the maximum transmitting time delay difference information that transmits from corresponding reception device length at interval.Power control unit 62 is determined gain coefficient according to the maximum transmitting time delay difference information that transmits from corresponding reception device.
Figure 36 represents the receiving equipment structure according to the 7th embodiment.This receiving equipment has the function of the transmission error of extracting known format data (PLj) and measurement data and generates the function of maximum transmitting time delay difference information according to transmission error rate.
Received ripple by the demodulator circuit demodulation.At this moment, spread demodulation device (SDEM) 15 uses extended code Ci when restituted signal sequence Si1, uses extended code C (PLj) when demodulation known format data (PLj).Demultiplexing unit 52 demultiplexes into burst Si1 and known format data (PLj) with the burst of regeneration.
Delay inequality detecting unit 111 is measured the transmission error rate of the known format data (PLj) of being regenerated, and generates maximum transmitting time delay difference information τ according to this transmission error rate.This maximum transmitting time delay difference information τ offers protection interval control unit (GCNT) 112, also has transmitter.Protection interval control unit 112 is determined protection at interval according to maximum transmitting time delay difference information τ, and protection delete cells 31 is at interval given in expression.Protection delete cells 31 is at interval protected at interval according to this expression deletion from received signal.
Figure 37 is the flow chart of delay inequality detecting unit 111 operations.In this example, suppose to have prepared a plurality of protection gap length data τ 0～τ n.Among protection gap length data τ 0～τ n, suppose " τ 0 " minimum, " τ n " maximum.During each reception known format data (PLj), carry out the process in this flow chart.
In step S1, extended code C (PLj) is provided with in spread demodulation device 15.Extended code C (PLj) uses when transmitter is expanded in known format data (PLj).Therefore, when received signal was reversed expansion, known format data (PLj) were reproduced.In step S2, the variable of protection gap length is specified in initialization.That is to say, be provided with " i=0 ".
At step S3, protection gap length data τ i is provided with in protection interval control unit 112.Because this moment " i=0 ", then " protection gap length data τ 0 " is provided with in protection interval control unit 123." protection gap length data τ 0 " has the minimum value of the possible data of being prepared.At this moment, demultiplexing unit 52 dateouts are so that the known format data (PLj) of being regenerated import delay inequality detecting unit 111.
At step S3, the error rate (error bit number) of check known format data (PLj) that regenerate.When error rate during greater than predetermined threshold, to suppose to obtain enough communication qualities, control forwards step S5 to.In step S5, whether test variable i can add 1.If of course, add after 1 in step S6 variable i, control turns back to step S3.
Therefore, in S6, in the time will increasing gradually at the protection gap length that protection interval control unit 112 is provided with, the error rate of known format data (PLj) is each linear measure longimetry at step S3.When the error rate of known format data (PLj) was equal to or less than thresholding, control was by step S7.Therefore, determine in the communication quality scope that the shortest possible protection can wanted in above-mentioned process at interval.At this moment, best protection is provided with in protection interval control unit 112 at interval.
At step S7, extended code Ci is provided with in spread demodulation device 15.Extended code Ci uses when transmitter spread signal sequence Si1 and Si2.After this, spread demodulation device 15 can be from received signal restituted signal sequence Si1.In step S8, step S3 is sent to transmitter to the protection gap length that S6 determines.
As mentioned above, in the 7th embodiment, protection length (and through-put power) at interval is determined measures transmission error rate simultaneously so that predetermined communication quality can be reserved.Therefore, can reserve and have the shortest possible protection at interval and the communication quality of wanting of through-put power.
The 8th embodiment
According to the communication system of the 8th embodiment is modification according to the communication system of the 7th embodiment.That is to say, the structure of the 7th embodiment for the protection that can determine to be provided with at receiving equipment at interval, this value is sent to transmitter.On the other hand, in the 8th embodiment, the transmission range between transmitter and the receiving equipment estimates that according to the protection gap length that will be arranged on receiving equipment results estimated is sent to transmitter.
Figure 38 represents the structure according to the transmitter of the 8th embodiment.This transmitter is basically with identical according to the transmitter of the 7th embodiment shown in Figure 35.But, provide protection interval control unit (GINSCNT) 81 and power control unit (PCNT) 82 according to the transmitter of the 8th embodiment, replace protection interval control unit (GINSCNT) 61 shown in Figure 35 and power control unit (PCNT) 62.Operating in of protection interval control unit 81 and power control unit 82 is top by being described with reference to the 4th embodiment.That is to say that protection interval control unit 81 is according to the protection length of determining from the transmission range information L that corresponding reception device transmitted to insert at interval.Power control unit 82 is according to determining gain coefficient α from the transmission range information L that corresponding reception device transmitted.
Figure 39 represents the structure according to the receiving equipment of eighth embodiment of the invention.This receiving equipment comprises distance estimations unit (LMES) 121, conversion table (TBL) 122 and protection interval control unit (GCNT) 123, replaces delay inequality detecting unit shown in Figure 36 111 and protection interval control unit 112.Distance estimations unit 121 and protection interval control unit 123 and the 7th the identical definite best protection gap length of embodiment.Then, conversion tables 122 are visited in distance estimations unit 121, and obtain the transmission range corresponding to determined protection gap length.Then, the transmission range information L that represents this transmission range is sent to transmitter.Conversion table 122 is corresponding to conversion table shown in Figure 28 85, and the corresponding relation between storage protection gap length and the transmission range.
Figure 40 is the flow chart of the operation of distance estimations shown in Figure 39 unit 121.In Figure 40, step S1 is to identical with according to the 7th embodiment of the process of S7.That is to say, in S7, determine to be arranged on the protection gap length τ i of receiving equipment at step S1.At step S11, protection gap length τ i is by converting transmission range information Li to reference to protection interval control unit 112 then.Then, in step S12, the resulting transmission range information of step S11 is sent to transmitter.
As mentioned above, according to the present invention because protection at interval and through-put power can suitably be provided with according to the maximum transmitting time delay difference that transmission link generated between the base station of service area in the cellular communication system and the mobile radio station, so can reduce the appearance of interference.Otherwise, because the transmission capacity of the transmission band of transmission link has obtained optimization, so communication system can effectively be worked with the total transmission capacity that increases.
Protection interval and through-put power can dynamically be controlled the also setting that can fix according to the maximum transmitting time delay of communication link between transmitter and the receiving equipment poor (or transmission range).For example, protection can determine that they can remain unchanged then, up to sign off with through-put power at interval when communicating by letter beginning.Also might dynamically adjust protection interval and through-put power in communication period.And, if the position of transmitter and receiving equipment does not change, can in initialization procedure, determine protection interval and through-put power.
And, definite although protection interval and through-put power are come according to maximum transmitting time delay poor (or transmission range) in the present invention, so can determine uniquely to protect at interval and the relation between the through-put power for example test, simulation etc.
Claims (4)
1. transmitter, being used to utilize OFDM to transmit will be by the common signal that receives of a plurality of receiving equipments, and described equipment comprises:
Protection is setting device at interval, is used for length is appended to this signal at interval corresponding to the protection of the maximum traffic delay of a plurality of transmission delays of a plurality of relatively receiving equipments.
2. transmitter, the signal that is used to utilize OFDM to transmit will to receive by each receiving equipment and will be by the common signal that receives of a plurality of receiving equipments, described transmitter comprises:
Protection is setting device at interval, is used to set protection and makes at interval to append to and will be equal to or greater than the protection length at interval that appends on any signal that will be received by each receiving equipment by the protection length at interval on the common signal that receives of a plurality of receiving equipments.
3. a receiving equipment is used to utilize OFDM to receive the signal that is transmitted by transmitter, and described signal is received jointly by a plurality of receiving equipments, and described receiving equipment comprises:
Protection is control device at interval, is used for length is set at the protection that will delete at interval at interval corresponding to the protection of the maximum traffic delay of a plurality of transmission delays of a plurality of relatively receiving equipments from described signal.
4. a receiving equipment is used for from the transmitter received signal, the signal that described transmitter utilizes OFDM to transmit will to be received by each receiving equipment and will be by the common signal that receives of a plurality of receiving equipments, and described receiving equipment comprises:
Protection is control device at interval, is used for that length is equal to or greater than the protection that appends on any signal that will be received by each receiving equipment and sets at interval from the protection that will be deleted by the common signal that receives of a plurality of receiving equipments at interval.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
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| PCT/JP2001/010357 WO2003047140A1 (en) | 2001-11-28 | 2001-11-28 | Orthogonal frequency-division multiplex transmission method |
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| CNB01823836XA Division CN100413232C (en) | 2001-11-28 | 2001-11-28 | Orthogonal frequency division multiplexing transmission method |
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| CN101188594A true CN101188594A (en) | 2008-05-28 |
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| CNB01823836XA Expired - Fee Related CN100413232C (en) | 2001-11-28 | 2001-11-28 | Orthogonal frequency division multiplexing transmission method |
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| JP (1) | JP3989439B2 (en) |
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| AU (1) | AU2002224120A1 (en) |
| DE (1) | DE60136393D1 (en) |
| WO (1) | WO2003047140A1 (en) |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107659343A (en) * | 2017-09-28 | 2018-02-02 | 上海大学 | Millimeter wave cooperation transmission method and device |
| CN111130614A (en) * | 2018-10-30 | 2020-05-08 | 华为技术有限公司 | Time delay indication method and device for satellite communication |
| CN111130614B (en) * | 2018-10-30 | 2021-10-26 | 华为技术有限公司 | Time delay indication method and device for satellite communication |
Also Published As
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| US8588187B2 (en) | 2013-11-19 |
| CN101188594B (en) | 2016-07-06 |
| EP1450505A4 (en) | 2007-08-15 |
| US20110142148A1 (en) | 2011-06-16 |
| AU2002224120A1 (en) | 2003-06-10 |
| JP3989439B2 (en) | 2007-10-10 |
| EP1450505B1 (en) | 2008-10-29 |
| US7843804B2 (en) | 2010-11-30 |
| CN101150556A (en) | 2008-03-26 |
| US20070183309A1 (en) | 2007-08-09 |
| WO2003047140A1 (en) | 2003-06-05 |
| EP1871015A1 (en) | 2007-12-26 |
| EP1871015B1 (en) | 2014-06-18 |
| CN1559114A (en) | 2004-12-29 |
| US20070183310A1 (en) | 2007-08-09 |
| EP1450505A1 (en) | 2004-08-25 |
| US20040213145A1 (en) | 2004-10-28 |
| CN100413232C (en) | 2008-08-20 |
| JPWO2003047140A1 (en) | 2005-04-14 |
| DE60136393D1 (en) | 2008-12-11 |
| CN101150556B (en) | 2015-11-25 |
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